1903 Help!?

I have found a 1903 at a local gun store. It has a welded 20 round BAR mag on it, however the receiver is labeled 1903 mark 1, with a 1.1 million serial number. The barrel is a 44 barrel with HS on it. The gun store says it is an Air Service rifle but it has a full stock not a smaller one like the AS rifles. They want 1700 for it, but I don't think it is an AS rifle. Was wondering if anyone knew anything. I remember reading that in Guadalcanal marines used to have people weld BAR mags on their 1903's. Also it does have the mark 1 mod for the Pederson device as well. Just don't want to pay too much for her.